Register March 2012 No. 675
Chapter Trans 308
REQUIREMENTS FOR TRAILER AND SEMI-TRAILER BRAKE, HITCH AND COUPLING, SAFETY CHAINS, CABLES AND LEVELING BARS
Trans 308.01 Emergency braking.
Trans 308.02 Brake tubing and hose, adequacy.
Trans 308.03 Brake tubing and hose connections.
Trans 308.04 Brake lining.
Trans 308.05 Brakes to be operative.
Trans 308.06 Single valve to operate all brakes.
Trans 308.07 Warning devices and gauges.
Trans 308.08 Electrical brake connections.
Trans 308.09 Brake performance.
Trans 308.10 Trailer and mobile home classification and standard minimum strength requirements of hitch and coupling.
Trans 308.11 Minimum strength ratings, coupling and ball, trailers and mobile homes.
Trans 308.12 Safety chains or cables for trailer and mobile homes.
Trans 308.13 Leveling bars.
Trans 308.14 Safety chain or cable for full trailers or trailer converter dollies connected by means of a pintle and tow bar eye.
Trans 308.01(1)
(1) Every truck or truck tractor equipped with air brakes, when used for towing other vehicles equipped with air brakes, shall be equipped with 2 means of activating the emergency features of the trailer brakes. One of these means shall operate automatically in the event of reduction of the towing vehicle air supply to a fixed pressure which shall not be lower than 20 pounds per square inch nor higher than 45 pounds per square inch. The other means shall be a manually controlled device readily operable by a person seated in the driving seat. Its emergency position or method of operation shall be clearly indicated. In no instance may the manual means be so arranged as to permit its use to prevent operation of the automatic means. The automatic and manual means required by this section may be, but are not required to be separate.
Trans 308.01(2)
(2) Every truck tractor and truck when used for towing other vehicles equipped with vacuum brakes, shall have, in addition to the single control required by
s. Trans 308.06 to operate all brakes of the combination, a second manual control device which can be used to operate the brakes on the towed vehicles in emergencies. Such second control shall be independent of other controls, unless the braking system be so arranged that failure of the pressure on which the second control depends will cause the towed vehicle brakes to be applied automatically. The second control is not required by this rule to provide modulated or graduated braking.
Trans 308.01(3)
(3) Air brake systems installed on towed vehicles shall be so designed, by the use of “no-bleed-back" relay emergency valves or equivalent devices, that the supply reservoir used to provide air for brakes shall be safeguarded against backflow of air to the towing vehicle upon reduction of the towing vehicle air pressure.
Trans 308.01(4)
(4) The requirements of
subs. (2) and
(3) shall not be applicable to motor vehicles in driveaway-towaway operations.
Trans 308.01 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.01 and am. (2),
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.02
Trans 308.02 Brake tubing and hose, adequacy. Brake tubing and brake hose shall be:
Trans 308.02(1)
(1) Designed and constructed of proper material and so installed and maintained as to insure proper continued functioning;
Trans 308.02(2)
(2) Sufficiently long and flexible as to accommodate without damage all normal motions of the parts to which they are attached;
Trans 308.02(3)
(3) Suitably secured against chafing, kinking, or other mechanical injury; and
Trans 308.02(4)(a)(a) Brake hose shall be so constructed as to insure adequate and reliable functioning and shall conform to the appropriate specification set forth in the SAE Standards for “Hydraulic Brake Hose Assemblies for use with Non-Petroleum Base Hydraulic Fluids," SAE J1401a; “Automotive Air Brake Hose and Hose Assemblies," J1402c; or “Vacuum Brake Hose," J1403a. (See 1980 SAE Handbook.)
Trans 308.02(4)(b)
(b) The above referred to SAE Standards are on file in the offices of the department of transportation, the secretary of state and the legislative reference bureau, and may be obtained from the Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, Pennsylvania 15096.
Trans 308.02 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.02 and am. (4),
Register, September, 1980, No. 297, eff. 10-1-80;
correction in (4) (b) made under s. 13.92 (4) (b) 6., Stats., Register March 2012 No. 675. Trans 308.03
Trans 308.03 Brake tubing and hose connections. All connections for air, vacuum, or hydraulic braking systems shall:
Trans 308.03(1)
(1) Be adequate in material and construction to insure proper continued functioning;
Trans 308.03(2)
(2) Be designed, constructed, installed and maintained so as to insure, when properly connected, an attachment free of leaks, constrictions, or other defects;
Trans 308.03(3)
(3) Have suitable provision in every detachable connection to afford reasonable assurance against accidental disconnection;
Trans 308.03(4)
(4) Have the vacuum brake engine manifold connection at least three-eighths inch in diameter.
Trans 308.03 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.03,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.04
Trans 308.04 Brake lining. The brake lining on every trailer type vehicle shall be so constructed, installed and maintained as not to be subject to excessive fading and grabbing and shall be adequate in thickness, means of attachment, and physical characteristics to provide for safe and reliable stopping of the vehicle.
Trans 308.04 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.04,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.05
Trans 308.05 Brakes to be operative. All brakes with which trailer-type vehicles are equipped shall be operative at all times except brakes need not be operative on disabled vehicles being towed.
Trans 308.05 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.05,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.06
Trans 308.06 Single valve to operate all brakes. Every motor vehicle, the date of manufacture of which is subsequent to June 30, 1953, which is equipped with power brakes, shall have the braking system so arranged that one application valve shall when applied operate all the service brakes on the motor vehicle or combination of motor vehicles. This requirement shall not be construed to prohibit motor vehicles from being equipped with an additional valve to be used to operate the brakes of a trailer or trailers. This section shall not be applicable to driveaway-towaway operations unless the brakes on such operations are designed to be operated by a single valve.
Trans 308.06 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.06,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.07(1)
(1)
Air brakes as provided in sub. (4). Every truck and truck tractor using compressed air for the operation of its own brakes or the brakes of any towed vehicle shall be equipped with a warning signal readily audible or visible to the driver, which will give continuous warning at all pressures below a fixed pressure not less than one-half of the compressor governor cut-out pressure. In addition, each such vehicle shall be equipped with a pressure gauge which will indicate to the driver the pressure in pounds per square inch available for braking.
Trans 308.07(2)
(2) Vacuum brakes as provided in sub. (4). Every truck and truck tractor using vacuum for the operation of its own brakes and vacuum for the brakes on any towed vehicle shall be equipped with a warning signal readily audible or visible to the driver, which will give continuous warning at any time the vacuum in the vehicle's supply reservoir is less than 8 inches of mercury. In addition, each such vehicle shall be equipped with a vacuum gauge which will indicate to the driver the vacuum in inches of mercury available for braking.
Trans 308.07(3)
(3) Maintenance. The warning devices and gauges required by this section shall be maintained in operative condition.
Trans 308.07(4)
(4) Application. This section applies to all combinations of property-carrying vehicles utilizing trailers or semi-trailers where the gross weight of the trailer or semi-trailer is 3000 pounds or more.
Trans 308.07 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.07,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.08
Trans 308.08 Electrical brake connections. All electrical wiring shall be mechanically and electrically adequate and free of short or open circuits. Suitable provision shall be made in every such detachable connection to afford reasonable assurance against connection in an incorrect manner or accidental disconnection. Detachable connections made by twisting together wires from the towed and towing units are prohibited. Precaution shall be taken to provide sufficient slack in the connecting wire or cable to accommodate without damage all normal motions of the parts to which they are attached.
Trans 308.08 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.08,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.09
Trans 308.09 Brake performance. Every combination of vehicles, at all times and under all conditions of loading, upon application of the service brake, shall be capable of stopping from a speed of 20 miles per hour in not more than 50 feet.
Trans 308.09 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.09,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.10
Trans 308.10 Trailer and mobile home classification and standard minimum strength requirements of hitch and coupling. Trans 308.10(1)(1)
Hitch definition. The hitch is that part of the connecting mechanism, including the coupling platform and its attaching members or weldments, which is attached to the towing vehicle.
Trans 308.10(2)
(2) Coupling definition. The coupling is that part of the connecting mechanism, including the coupling and its attaching members or weldments, which is attached to the trailer or mobile home and by which connection is made to the hitch.
Trans 308.10(3)
(3) Trailer and mobile home classification. Trailers and mobile homes shall be classified according to the following gross weights, which gross weight shall include the weight of the vehicle and the actual load carried.
Trans 308.10(3)(b)
(b) Class 2—All vehicles in excess of 2000 lbs. gross weight but not exceeding 3500 lbs. gross weight.
Trans 308.10(3)(c)
(c) Class 3—All vehicles in excess of 3500 lbs. gross weight and not exceeding 5000 lbs. gross weight.
Trans 308.10(3)(d)
(d) Class 4—All vehicles with gross weight, in excess of 5000 lbs. but not to exceed 10,000 lbs.
Trans 308.10(4)
(4) Strength rating for trailer and mobile home couplings and for class 5 vehicle hitches. Trans 308.10(4)(a)(a) The trailer or mobile home coupling shall be of such design as to conform to the minimum strength requirements set forth in
par. (b). Where a ball-and-socket type of coupling is used, the ball must conform to the minimum load ratings of the mating coupling.
Trans 308.10(4)(b)
(b) Minimum strength ratings for the coupling used in conjunction with specific classes of trailers and mobile homes and for the hitch used in conjunction with Class 5 vehicles.
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See PDF for table 
Trans 308.10(5)
(5) Coupling, mounting. Each coupling is to be mounted to the attaching member by bolting, welding or riveting in such manner that the maximum loading required for the coupling designation shown in
sub. (4) (b) is safely and adequately transferred to that member.
Trans 308.10(6)
(6) Required mechanism. Each hitch and coupling, regardless of classification, must be equipped with a manually operated mechanism so adapted as to prevent disengagement of the unit while in operation.
Trans 308.10(7)(a)(a) The hitch and its coupling platform shall be of such design and shall be so attached to the towing vehicle as to safely and adequately handle the gross load of trailer or mobile home including contents thereof.
Trans 308.10 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; emerg. am. (3) (a) to (d) and (4) (b), cr. (3) (e), r. (4) (c), eff. 4-14-80; renum. from MVD 8.10 and am. (3) (a) to (d) and (4) (b), cr. (3) (e), r. (4) (c),
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.11
Trans 308.11 Minimum strength ratings, coupling and ball, trailers and mobile homes. Minimum strength ratings for the coupling and ball for trailers and mobile homes are as follows:
-
See PDF for table Trans 308.11 History
History: Cr.
Register, July, 1968, No. 151, eff. 8-1-68; renum. from MVD 8.11,
Register, September, 1980, No. 297, eff. 10-1-80.
Trans 308.12
Trans 308.12 Safety chains or cables for trailer and mobile homes.
